Safety wrench for electrical fuses



y 1956 1.. VERKUIL 2,743,640

SAFETY WRENCH FOR ELECTRICAL FUSES Filed March 25, 1953 INVENTOR LEO L VEfi/(U/L ATTORNEY nited States Patent SAFETY WRENH FOR ELECTRICAL FUSES Leo L. Verkuil, Norwalk, Conn. Application March 25, 1953, Serial No. 344,618

Claims. (Cl. lib-6d) This invention relates to safety devices for handling, particularly by the householder, of electrical fuses of the threaded type, in inserting or removing them from their conductive sockets.

It is well-known that fuse blocks are of various types of construction and in many of them conductive parts such as the threaded socket portion itself or even wires and connecting terminals are frequently positioned or located so that manual contact therewith is possible and that there is present the risk of electrical shock particularly in Wet cellars and other grounded locations where fuse blocks and fuse boxes are often located. Moreover, in commercial forms of fuses the portion that has to be grasped by the fingers is usually of small dimension so that the fingers of the hand can be brought into close proximity to conductive parts and also these portions of threaded fuse structures are of various external shapes. Where the fuse block contains a number of threaded sockets the latter are usually closely compacted together, frequently making it difficult to manually apply turning torque to the fuse. One of the dominant aims of this invention is to provide a simple and practical safety device or Wrench that will make it possible to circumvent such risks as above mentioned and self-adaptable, by reason of certain features of its construction, to meet dependably such widely varying conditions met with in practice like those above mentioned. Another object is to provide a device of the just mentioned character which will be easy and simple for the layman to use and can be economically manufactured.

in the accompanying drawing in which is shown by Way of illustration a preferred embodiment of my invention and in which similar reference characters refer to similar parts throughout the several views,

Figure l is a side elevation of the safety wrench;

Figure 2 is an end elevation as seen ,,from the left in Figure 1;

Figure 3 is an end elevation as seen from the right in Figure l;

Fi ure 4 is a central longitudinal vertical sectional view as seen along the line 4-4 of Figures 2 and 3, and

Figure 5 is a diagrammatic representation of a fuse block or box showing, illustratively, several fuses of various shapes carried thereby, all as seen in elevation.

Figures 1-4 the safety wrench, generally indicated by the reference character W comprises a relatively thinwalled tubular body of insulating material having features of construction to facilitate various coactions later described and at the same time to facilitate production of the device as by molding it out of a suitable moldable and curable non-conductive material; the latter may be of any of the well-known plastic materials including rubber and like compounds that are curable to relative hardness or stiffness and preferably also of characteristics that give to the cured material a toughness that substantially avoids brittleness. The relatively thin walls, about to be described in detail, may thus and preferably have a suitable degree of give, such as a slight distortability out of true round, as viewed in Figures 2 and 3, a distortability from which, though the material is relatively hard, the walls or parts thereof readily recover when relieved of stress.

For purpose of molding the device W is externally preferably substantially cylindrical and for ease of grasping its external cylindrical surface may also be fluted as at it); the flutes ll) extend parallel to the axis of the device, from either end thereof to terminate at or in a central band-like or peripherally extending rib 17 for a purpose later described and which may project peripherally beyond the fiuted portions to either side thereof as is better shown in Figures 1 and 4.

The device is thus externally divided into two external finger-gripping portions 11, 12, either of which may be solidly and strongly grasped by the thumb and fingers of the hand according to which one of the two internal fuse-gripping portions provided by and in the internal faces thereof, is to be employed in engaging and turning a particular threaded fuse. The internal fuse-gripping portion at the left, as viewed in Figure l, is shown in elevation in Figure 2 and in vertical central section in Figure 4 where it is indicated as a Whole by the reference character 13 and correspondingly the internal righ'*-hand fuse-gripping portion, generally indicated as a whole at 14 is shown in elevation in Figure 3 and in section in Figure 4; the internal surface of each is in general frusto-conical and hence the wall thickness becomes less as the open end is reached and is broken up, in general axial direction, by internal lengthwise extending depressions or grooves 15 and 16 respectively in order to facilitate distortability and straining as above described. In response to internal stresses that result from inter-engagement with the differently shaped heads or finger-gripping portions of the threaded fuses; the inside faces of the fuse-gripping portions 13, 14 are tapered, being of diminishing distance from the axis of the device W (see Figure 4) as these surfaces progress from the respective open ends of the device to substantially the midportion thereof where I preferably provide a transverse diaphragm 18 which is formed, as by molding and curing, integrally with the rest of the device. The diaphragm 18 can be and preferably is relatively thin; though thin, diaphragm 18 offers relatively rigid peripheral support to the generally cylindrical walls of the device, at the center thereof, and it can thus serve substantially as a barrier against the transmission of distorting stresses to one fuse-gripping portion when the finger-grip portion at the other end thereof is subjected to the grasp or grip by the thumb and fingers in applying the device to a threaded fuse. In these actions, the external peripheral rib 17 can take part or co-act. A tight hand grip, often necessary to dislodge a threaded fuse, upon one or the other of the external finger grip portions ill, 12, while it may somewhat distort the gripped end into a slightly out-of-round shape by pressing opposed portions somewhat inwardly in a direction toward the axis, is thus prevented from having opposite distorting reactions upon the fuse-gripping portion that is operative at the other end of the device, and in that manner security of gripping and holding the fuse so that it will not rotatively slip relative to the device, is assured.

In Figure 5, a fuse block or a fuse box is diagrammatically indicated at 20; it is of any usual or suitable construction such as those earlier above described so that details of exposed conductive socket sleeves or conductors or connectors need not be shown; as indicated in Figure 5 the fuse carrier 20 may be constructed to accommodate more than one threaded fuse and several are there shown. One of the latter is indicated at 21, being of the more common type in which the head or the part to be grasped has an external circular periphery 22, and in practice it greases is found that the diameter of the periphery 22 varies. Accordingly, and now referring to Figures 2, 3 and 4, the internal tapered faces of the fuse gripping, parts 13, 14 pro vide two ranges of diameters of screw fuses 21 so that a range of larger diameters of peripheries 22 is enterable into the 'left hand fuse gripping portion 13 and an adjacent range of smaller diameters is enterable into the right hand fuse gripping portion 14.

The lengthwise extending internal depressions or grooves 15 and 16 peripherally subdivide and break up the internal tapered arcuate gripping surfaces, illustratively each into six portions of equal arcuate extent, as shown at 23 in Figures 2 and 4 for the fuse-grip 13 and at 24 in Figures 3 and 4 for the fuse-grip 14. Because of the internal grooves 15 and 16 and the resultant thinning of the walls thereat, each sub-division 23 or 24 can more readily give, in general radial direction relative to its neighbor or neighbors and thus when the device is forced or wedged onto a fuse-like fuse 21 of Figure 5, thelatter is more securely gripped by these peripherally sub-dividedparts or areas and the latter are readily selfaccommodating to any out-of-round shape or condition of thefuse part 22. Moreover, some times the periphery 22 of threaded fuses 21, as when fuse body and head are made of glass, is provided with several series of small projections as indicated at 25, and in such case gripping co-action is also facilitated by the above described relative yieldability between the parts 23 at the one end or between parts 24 at the other end of the device, and moreover, the edges of the grooves 15 or of grooves 16, as the case may be, are available to inter-engage with an endmost projection 25 of one or more of the peripherally distributed series of projections 25. Such inter-engagement is facilitated by the just described relative straining of one arcuate part relative to its neighbor.

The internal longitudinal depressions or grooves 15 at one end and depressions or grooves 16 at the other are preferably equi-angularly located and are preferably, as above indicated, six in number. As for the grooves 16 and as is better shown in Figure 3, I locate them at the apexes of a hexagon and shape each groove 16 to provide a re-entrant angle corresponding to the external angle of a hexagon. These grooves, though tapered, retain the just described re-entrant angularity throughout their length and by means of them, threaded fuses, of the type shown at 26 in Figure 5, in which the fuse head is externally hexagonal as at 27, may be engaged and gripped for turning, the several apexes of the hexagonal head 27 being receivable respectively into the corresponding reentrant angles of the grooves 16; the latter, being tapered, provide fora range of variation in the size of the hexagonal27 of the fuses 26 and the latter, by the just de scribed inter-engagement with or without wedging ac tion, may be safely turned. Moreover, hexagonal fuse heads are frequently made of glass and are not always of precise hexagonal shape; nevertheless, the above described distortability of my device provides for good interlocking engagement when the right hand end thereof is set over the fuse 26, while straining of the left hand finger-grip part is prevented, as above described, from disturbing the interlocking with the fuse itself.

The longitudinal internal grooves 15, at the left hand fuse-grip portion 13, are also preferably 'cqui-angularly spaced, and are six in number; while thus located to correspond to the apexes of a hexagon, they are shaped, as is better shown in Figure 2, to be relatively shallow'and of substantial dimension in peripheral direction. Thinning of the fuse-grip walls at corresponding longitudinal regions, ,to achieve the above described distortability, is thus dependably provided, but also the grooves 15 are thereby conformed, being also tapered, for the reception of the truncated apexes 28 of the type of fuse shown at 29 in Figure 5, where the fuse head is usually of glass, generally hexagonal but with truncated apexes, and not always of precise geometric configuration or of uniformity throughout. The wide shallow grooves 15 provide for ease of reception therein of the truncated apexes of fuses 29 throughout such vagaries of configuration thereof as just noted, and the relative bodily movement between the parts 23, permitted by the thinned-out walls at the grooves 15, insures dependable self-accommodation of the fuse-grip portion 13 to the fuse 29, undisturbed by strains caused by manual stresses applied externally to the finger-grip portion 12 at the other end of the device W, in the manner earlier above described.

The device W, while relatively rigid, will be seen to be of dependable action in use, being provided, by the above described structural features, with recoverable distortability in order that it dependably accommodates, under the stress of being manually forced over and on to a threaded fuse, to the substantial variety and vagaries and of nonuniformities of threaded fuse head conformations with which the average householder meets, and though pressed into frictional or other interlocking grip at one end, the structural features of the device insure that the manual straining thereof at the other end for purposes of turning the fuse do not detrimentally upset the grip on the fuse itself.

As above noted the device is preferably made of an insulating material which may be relatively hard or rigid, yet the structural features above described, such as the longitudinal thinning of the. walls along the grooves 15 and 16 permits sufiicient flexing, without fracture, when a misshapen or unsymmetrical fuse head strains one side portion radially to greater extent than some other side portion. For example, a fuse head such as the head 22 might'be out-of-round but when either end of the device is wedged on to it, a hinge-like action of the side walls at the bottom of the grooves 15 or 16 assures gripping selfaccommodation of the device to the fuse head, with resultant certainty of action. In like manner a hexagonal head such as 27 in Figure 5 might be unsymmetrical and might have one apex projecting more than another and in that case the wedging action of the apexes in the reentrant angular grooves 16 can strain the device to conformity by hinge-like action of the thinned side walls at the bottom of the grooves 16. In similar manner the thinned walls at the bottom of the grooves 15 which in shape are truncated re-entrant angles (see Figure 2) can flex or easily distort for self-accommodation of the device to irregularity of shape of a fuse head like the head shown at 29 in Figure 5. For symmetry of flexing action of these thinned longitudinal wall portions, the grooves 15 and 16 I and the external ribs 10 and intervening valleys (see Figures 2 and 3) may be symmetrically disposed in relation to one another; for example, the grooves at one end and the grooves 16 at the other may underlie and enter into the material of an external rib of the fluting as shown in Figures 2 and 3, leaving uniformly distributed external valleys between successive internal grooves so that if flexing occurs also where the walls are thinned out by the external valleys, desirable uniformity of action is achieved throughout the peripheral extent of each fuse gripping end.

Such certainty and dependability of functioning aids in avoiding risks of electrical shock, for the avoidance of malfunctioning in turn avoids manifold manipulation and possible exploration on the part of the layman such as might lead to manual contact with a conductive part. The device is of relatively light weight, utilizes minimum of material and lends itself to quantity production by molding operations as above indicated.

This application is a continuation-in-part of my application Serial No. 201,731, filed December 20, 1950, and now abandoned.

I claim:

1. A safety fuse wrench for rigid wedging manually onto the periphery of the head of a screw-threaded fuse, said wrench being non-distortable in the direction of the axis about which it is to be turned whereby wedging pressure may be manually applied to it at a part thereof fixedly remote from where the wrench is to be wedged onto the fuse, said wrench comprising a relatively thin-walled sleeve of relatively rigid insulating material having opposite open ends the walls of which are relatively rigid as a whole and are interiorly tapered and substantially frustoconical with six equi-angularly spaced longitudinally extending interior grooves which form out of said relatively rigid Walls of insulating material longitudinally extending thinner and therefore weakened wall portions that provide longitudinal integral connections between the intervening relatively rigid thicker wall portions, said connections being thereby adapted to recoverably yield upon straining and radial movement of said thicker intervening wall portions relative to one another, in response to axial pressure applied manually as aforesaid, to accommodate them to irregularities of fuse-head shape and to effect substantially uniform wedge-like engagement with differently sized heads of screw-threaded fuses in response to manual pressure applied to the wrench in axial direction as aforesaid, said walls at said opposite ends having ex ternal surfaces for direct grasping at either end by the fingers of the hand for applying wedging pressure in axial direction at the end remote fro-m that entered onto a fuse head and for then conveying rotative movement to the fuse wedged into the open other end, the sleeve having a thin transverse radiallydncompressible diaphragm at its center to resist straining, in radial outward direction, of said intervening portions that grip a fuse at one end, by radially inward strain of portions of the other end caused by gripping of the latter externally, the internal grooves at one end forming re-entrant angles substantially mating with the external angles of a hexagon and the internal grooves at the other side forming truncated angles in crosssection and substantially mating with the external truncated angles of a modified hexagon.

2. A safety fuse wrench as claimed in claim 1 in which the walls of said sleeve are externally fiuted in directions lengthwise of the sleeve by alternated ribs and valleys, the latter being peripherally distributed relative to said interior grooves so that said grooves are juxtaposed internally each to an external rib, with each groove internally entering the body of the rib for effecting substantial uniformity of the aforesaid recoverable relative radial movements.

3. A double-ended safety fuse wrench for rigid wedging manually onto the periphery of the head of a screwthreaded fuse, said wrench being non-distortable in the direction of the axis about which .it is to be turned whereby wedging pressure may be manually applied to it at a part thereof fixedly remote from where the wrench is to be wedged onto the fuse, said wrench comprising a molded sleeve-like relatively rigid body of relatively rigid insulating material having an external substantially cylindrical surface with internal coaxial inwardly tapered surfaces extending inwardly from opposite ends of said body for receiving therein and at either end differently sized heads of threaded fuses and thereby leaving the external surfaces at the other and remote end of said body to serve as a relatively rigid hand grip for turning the wrench, the internal surface at one end being sub-divided by six longitudinally extending and equi-angularly spaced grooves which are re-entrantly angular in cross-section and the internal surface at the other end being subdivided by six longitudinally extending and equi-angularly spaced grooves which in cross-section have the shape of a truncated angle, said grooves providing at their bases longitudinal thinned wall portions in the said relatively rigid insulating material of the sleeve-like body which portions may distort without fracture when intervening thicker and rigid wall portions are non-uniformly displaced in radial direction by unsymmetrical fuse heads.

4. A safety fuse wrench for rigid wedging manually onto the periphery of the head of a screw-threaded fuse, said wrench being non-distortable in the direction of the axis about which it is to be turned whereby wedging pressure may be manually applied to it at a part thereof fixedly remote from where the wrench is to be wedged onto the fuse, said wrench comprising a molded sleeve-like relatively rigid body of relatively rigid insulating material having an external substantially cylindrical surface providing a relatively rigid hand-grip at one end of the sleeve for turning the wrench and having at the other end of the sleeve fuse-head engaging portions in the form of an internal coaxial inwardly tapered and substantially frustoconical surface which is sub-divided by six longitudinally extending and eqni-angularly spaced grooves which are substantially re-entrantly angular in cross section and which provide longitudinal thinned wall portions in the said relatively rigid insulating material of the sleeve-like body which portions may distort without fracture when intervening thicker and rigid frusto-conical wall portions are non-uniformly strained in radial direction by unsymmetrical fuse heads.

5. A safety fuse wrench for rigid wedging manually onto the periphery of the head of a screw-threaded fuse, said wrench being non-distortable in the direction of the axis about which it is to be turned whereby wedging pressure may be manually applied'to it at a part thereof fixedly remote from where the wrench it to be wedged onto the fuse, said wrench comprising a molded sleeve-like relatively rigid body of relatively rigid insulating material having an external substantially cylindrical surface providing a relatively rigid hand-grip at one end of the sleeve for turning the wrench and having at the other end of the sleeve fuse-head engaging portions in the form of an internal coaxial inwardly tapered and substantially frustoconical surface which is sub-divided by six longitudinally extending and equi-angularly spaced grooves which have the shape in cross-section of a truncated angle and which provide longitudinal thinned wall portions in the said relatively rigid insulating material of the sleeve-like body which portions may distort without fracture when intervening thicker and rigid frusto-conical wall portions are non-uniformly strained in radial direction by unsymmetrial fuse heads.

References Cited in the file of this patent UNITED STATES PATENTS 1,952,660 Dryden Mar. 27, 1934 1,954,422 McIntyre Apr. 10, 1934 1,960,531 Driscoll May 29, 1934 2,491,089 Cowden Dec. 13, 1949 FOREIGN PATENTS 21,977 Great Britain Oct. 5, 1907 19,033 Australia Feb. 21, 1935 

